1. Benevolence isn't necessarily irrational. Just as valuing art, or collecting stamps, or solving jigsaw puzzles isn't irrational but ennobling recreation or "play", helping people at personal expense could no more be irrational. In fact there are some "unworthy" people that could be inspired to respect themselves and others, if someone they respected put faith in them. People are nonlinear in that regard; an honest man distrusted my be encouraged to commit an opportunistic crime, while a dishonest/pragmatic man may be encouraged not to disappoint someone who trust them.
2. ID projection - I didn't mean to imply you didn't love yourself. Yet there are some (I've heard, single-source, that often PETA-terrorists were abused children, and attempt to be "Batman" as it were, by attacking medical labs, et).
3. You wrote: "I am not trying to understand only my own instincts, I am trying to crack the nature/functional purpose of that instinct in general. That is why this is, in many ways, a philosophical issue.".
Loving cute, furry animals is indeed instinctive. An account (Cialdini, "Influence"):
"Turkey mothers are good mothers-loving, watchful, and protective. They spend much of their time tending, warming, cleaning and huddling the young beneath them...But there is something odd about their method. Virtually all of this mothering is triggered by one thing: the "cheep-cheep" sound of young turkey chicks...If a chick(doesn't) ... mother will ignore or sometimes kill it...W.M. Fox...(did) an experiment involving a mother turkey and a stuffed polecat. For a mother turkey, a polecat is a natural enemy whose approach is to be greeted with squawking, pecking, clawing rage...even a stuffed model of a polecat, ...received an immediate and furious attack. When, however, the same stuffed replica carried inside it a small recorder that played the "cheep-cheep" sound of baby turkeys, the mother not only accepted the oncoming polecat but gathered it underneath her. When the machine was turned off, the poleat model against drew a vicious attack."
Our instincts and primal drives motivate us to do "irrational" things, in a context which doesn't recognize our nature as rational-animals. The modern, atheist context which insults man for being part animal and not a disembodied intellect, rather than celebrates man as nature's greatest ongoing work-in-progress to date.
4. "First of all, why would an Objectivist wonder what is normal?"
It could be argued the only "Objectivists" are Rand, Peikoff, and anyone that absolutely adheres to their formal philosophy. So I read the question as "what would Rand do". If you phrased the question as, "Am I irrational? What is the value in, apparently altruisticaly, spending time and money to make an animal feel good"? I wouldn't have assume you were trying to be like someone else. There is on ongoing thread about "cult" Objectivism. A "Randriod" would ask, "how can I be like Rand"? Sorry for the offense.
5. How do you know they are "normal"?
If most people are altruistic, and you aspire and become more rationaly egoistic, are you not becoming "abnormal" and "deviant", even if more rational?
6. "if an Objectivist should ask, why has an Objectivist taken the time to answer?"
We are here, and I enjoy the discourse. I like finding out when I'm wrong, and occasionaly venting my wrath on the pervasive evil that poisons minds. Its cognitive exercise. Perhaps I'll meet some friends.
7. Taking license to re-phrase the question I've asked myself after reading VOS, and addressing its premise, since Rand answers our cultural misconceptions about altruism and selfishness:
"Am I irrational? What is the value in, apparently altruisticaly, spending time and money to make an animal feel good"?
The premises (which Rand addresses in VOS):
1. Its evil to be selfish; selfish people use and abuse others because to be perfectly rational, you would use other living things as means to your ends, rather than honoring them as ends in themselves.
The fallacy here is equating selfishness with sacrificing others to self. Rational beings recognize living organisms are ends in themselves, with independent wills.
2. Since selfish people hurt and abuse others, its good people that are altruistic; they take consider others before themselves.
The fallacy here is that altruism is stable, leading to the good. It isn't. It plunders the best, rewards the best cheaters, ruins everyones sense-of-life, and results in despotism and war.
Rand said altruistic sacrifice is giving the neighbors child a cake, while yours go hungry. Being selfish is feeding your own children while you go hungry, because seeing them happy is of greater value to you than being fed yourself. Rational animals understand their animal nature to love and enjoy other animals.